Mo Farah poses with his trademark 'Mobot' celebration as he wins the Men's 5000m race at Muller Anniversary Games

Mo Farah has worked to ensure he will not be taken by surprise by a rival as he bids to complete a historic 'double double' of Olympic long-distance titles in Rio on Saturday.

Already the first British track and field athlete to win three Olympic crowns, the 33-year-old will bid to continue his relentless global domination of distance running when he goes for gold over 5,000 metres.

Success would make him only the second man after 'Flying Finn' Lasse Viren to win 5,000m and 10,000m gold at two Games. It would also, surely, make him Great Britain's finest ever athlete to grace the track.

And he has done his research. Since he was shocked by an Ethiopian he had never even heard of, Ibrahim Jeilan, in the 10,000m final at the 2011 World Championships in Daegu - his last loss at a major - he has left no stone unturned in his preparations.

"I am a geek," he said.

"I do watch races and I do try and learn something about it, look at it, see what I could do.

"I watch myself a little bit, just try and do my homework a bit. I had to learn the hard way, in Daegu. I didn't even have a clue who he was, nobody knew.

"From there I was like, 'What do I need to do? Who do I need to be aware of?' You just have to understand a little bit more."

The Londoner knows, though, this one will be the toughest test of his career. Tougher than 2012, tougher than his back-to-back double world title triumphs in 2013 and 2015. The Ethiopians are out to end his reign.

Getting over the 10,000m is becoming harder the older he gets, his legs taking longer to recover.

And he knows the trio of challengers - Muktar Edris, Dejen Gebremeskel and Hagos Gebrhiwet - he will face this time around have the potential to upset him, provided they can run the finishing speed out of him by making the race quick.

He is also wary of another trip, thanks to his long, loping stride, after having to drag himself off the track to win the 10,000m and only just keeping his balance following a clip in the heats of the 5,000m.

Viren too fell on his way to 10,000m glory at the 1972 Munich Olympics, not that Farah is too aware of his place in history.

"I'm too young to know this," said the die-hard Arsenal fan. "When I started athletics I used to love football and didn't even know Steve Cram. The first time I met him I was like, 'Who's this guy?'

"Then later on I watched him on YouTube and videos and understood about the sport. I had to learn about the sport."

Saturday night's race will also mark the end of an era - Farah's last on the track at an Olympics. His last on the track full stop will come at next year's World Championships in London.

"Good things must come to an end, right?" he said. "Why not end it on the track where you started?"